Beyond the box, however, both tablets can do so much more. Thanks to customized microSD expansion cards from RootMyNookHD and N2A Cards, you can turn your Nook into a full-blown Android tablet.

The advantages in doing so are plain: Not only do you get full access to Google Play and all the apps therein (Barnes & Noble limits you to a curated app store), you also get freedom from Barnes & Noble's e-book ecosystem. In other words, you can install all the e-book apps you want: Nook, Kindle, Kobo, Google Books, and so on.

You also get a more traditional Android interface, one you can tweak with themes, widgets, launchers, and the like. And best of all, this transformation occurs entirely on a microSD card. Using it doesn't void your warranty, and you can return to the original B&N operating system any time just by popping out the card (or using a boot menu to switch between the two).

I've spent the past few weeks checking out the latest versions from N2A Cards and RootMyNookHD, trying to figure out if one is markedly better than the other. I won't keep you in suspense: They're both great. But I did find a few pros and cons with each, so allow me to run down my experiences to help you decide which one to buy.

Availability and compatibility

This is the rather blank canvas that greets you in N2A Cards' product. But there's still plenty of Jelly Bean power under the hood.
Screenshot by Rick Broida/CNET

You can either buy a preconfigured microSD card or download an image file to install on your own compatible card. The latter option can save you money, especially if you're looking for a higher-capacity card (see the next section).

For what it's worth, I've used the download option a couple times, and while the write-to-card process is slow (60 to 90 minutes), it's simple and it works.

RootMyNook doesn't offer a Jelly Bean option for the Nook Color, but does have Android 4.2 for the Nook Tablet and Nook HD, and Android 4.1 for the Nook HD+. However, you'll have to order a card; at press time, a planned download service wasn't ready.

Price

N2A Cards charges a bit more: $29.99, $39.99, and $59.99 for the same capacities. But the download versions are all priced at $19.99. I went shopping at Newegg for a compatible 32GB card and found an A-Data Class 10 for $17.99 after rebate. That works out to $37.98 for a 32GB N2A Card.

Many readers have already pointed out many times that you can make your own Android-bootable card more or less for free (do a Web search for it), but that takes some technical expertise. Here you're getting a ready-to-roll product and very competent tech support.

Presentation

Android is Android, right? Wrong. Although both products rely on CyanogenMod 10, an aftermarket Android distribution, they deliver a very different out-of-box experience.

N2A Cards provides an almost austere interface (see above). The home screen features an animated spinning-galaxy wallpaper, but only seven stock apps and N2A Cards' App Corner, which directs you to various batches of "recommended" items. Ultimately, it's bare-bones Android, which may appeal to users who dislike shovelware but do like starting more or less from scratch.

RootMyNook definitely wins the "wow" contest, delivering not only a pretty animated background, but also a full complement of the apps most people want: Facebook and Twitter, Nook and Kindle, Slacker and Pandora, Netflix and YouTube, and so on. Even Amazon's Appstore is there, right alongside Google Play.

Based on aesthetics alone, I like RootMyNook better. It wouldn't be difficult to make N2A Cards look exactly the same, but I, for one, like having my favorite apps at the ready.

Features and performance

Pretty much everything works as it should on both tablets running both cards: speakers, microphone, buttons, and so forth. Want to place a (voice-only) call over Skype? Go ahead.

I also tried pairing the Nooks with an Edifier Bric BT Bluetooth speaker. The RootMyNook install worked just fine, and in no time I was streaming audio from the likes of iHeartRadio. But N2A simply wouldn't pair, and although I reported the issue to the developer a couple weeks ago, at the time of this writing he didn't yet have a working fix. They're still hard at work on it, however.

On the app front, everything I threw at the two cards worked flawlessly, with one exception: I couldn't get magazine reader Zinio to run properly on either one, which most likely points to an issue with CyanogenMod. That's a disappointment, as I really love reading magazines on tablets like these.

Both developers routinely issue card updates, but they can be problematic because there's really no way to apply them -- not without wiping your card and losing all your apps and settings. N2A Cards, for its part, offers a backup option that will preserve and restore your app data (though not your apps), thus simplifying the update process at least somewhat. RootMyNook currently offers no such solution.

Conclusion

If you're looking for an easy and affordable way to transform your Nook HD or HD+ into an Android tablet, you can't go wrong with N2A Cards or RootMyNookHD. I've tested both at length and find them stable, effective products. And both developers offer crackerjack support.

I'm really hard-pressed to pick an outright winner. I like RootMyNook's out-of-box experience and Bluetooth support, but appreciate N2A Cards' download option and backup capabilities (such as they are).

Guess you'll have to weigh the pros and cons for yourself, then pick one. I suspect you won't be disappointed either way.